1. Technical Field of the Invention
The invention relates to systems for quantifying physical performance, and the use of gesture recognition to control system operation.
2. Background of the Prior Art
Body-worn (“wearable”) sensors are used by exercisers to measure physiological parameters such as heart rate and to infer caloric expenditure. Additionally, walkers, runners and cyclists use wearable sensors that measure physical performance parameters such as distance traveled and pace/movement speed. These devices improve motivation and provide valuable feedback for fitness program management. They are particularly popular for types of exercise that are mostly continuous in nature, in that the exercise sessions are typically uninterrupted until the session is completed. For example, a three mile run or a 10 mile bike ride.
By contrast, exercise routines designed to test and/or improve muscular strength and power are typically episodic or repetitive in nature; such routines are comprised of a number of distinct movements, “events” or “bouts” performed by the user. These movements, events or bouts of exercise are typically defined as sets and repetitions (“reps”) to be performed. For example, the user may transition from one type of exercise, moving from a bench press to a squat, wherein a prescribed number of sets, repetitions and weight (load) for each exercise are performed. For the purposes of this application, the term “exercise set” shall mean one or more repetitions of a specific exercise that is performed continuously until completion. An “exercise set” has a distinct beginning and ending point. By way of example, the user may perform 10 repetitions of a bench press, which would comprise one “exercise set.”
Strength and power training routines utilizing traditional training implements such as barbells, dumbbells, cables, kettle bells, medicine balls and similar have few practical means of objectively quantifying the user's physical performance, or providing real-time objective feedback beyond the user counting sets and reps performed for each type of exercise and then manually recording the weight (load) used for each exercise.
Biomechanics laboratories employ sophisticated and expensive instrumentation to measure such quantities as acceleration, velocity, power and mechanical work during weight lifting or similar training endeavors. However, this type of instrumentation requires laborious set-up procedures and post-processing for the data accumulated during testing or training.
Several studies have confirmed that accelerometers can be used to measure performance factors of interest to exercisers such as caloric expenditure, acceleration, velocity, force, mechanical work and similar. A research paper titled “Applicability of Triaxial Accelerometer for Energy Expenditure Calculation in Weight Lifting” concluded that a tri-axial accelerometer integrated into a wristwatch “seems to be applicable for energy expenditure estimation in weight lifting.”
The study “Barbell Acceleration Analysis on Various Intensities of Weightlifting” noted that biomechanical characteristics of weightlifting techniques have been studied using accelerometers. Parameters measured included barbell trajectory, acceleration, and velocity as well as mechanical work and power output.
Several manufacturers of commercial/institutional grade strength training machines, often referred to as “selectorized” or “variable resistance” machines, incorporate means for quantifying the work performed by the user. However, such equipment is quite expensive, offers a limited variety of movement patterns and is typically only available at health clubs and rehabilitation facilities. And because such machines typically constrain or support the user during their use, some experts characterize this type of exercise as “less functional” and therefore less valuable for certain user groups than “free weights” and other “functional training” methodologies.
Several published U.S. patent applications teach sensor systems for quantifying the user's physical performance during strength and conditioning programs. One such prior art system that teaches the use of an accelerometer mounted in a glove worn by the user during training is U.S. 2008/0204225. The proposed device mounts two or more sensors on the user's body to assist in identifying the prescribed movement pattern from the resulting sensor signals. The invention teaches that the preferred location of the base station is near the user so the user can easily hit the “Start” and “Stop” buttons before and after each “exercise set” respectively.
The prior art system, U.S. 2008/0090703, teaches that the invention's sensor can be affixed to either a piece of equipment, for example, a weight stack of a selectorized strength machine or to a barbell, or alternatively can be worn on the user's body.
U.S. 2009/0069722 teaches a system where the sensing means, an accelerometer, can be attached to either the training implement to be lifted or it can be worn on the exerciser's waist belt. The user is instructed to press a key to initiate the system's calibration procedure in advance of starting the exercise.
Studies performed in a laboratory environment may rely on technicians and post-processing of the sensor signals to extract spurious signals from those produced by the intended movement. Spurious signals can be produced from such user activities as changing the load on the barbell, assuming a correct position for the next exercise or even brushing the hair from one's face or wiping sweat from one's brow.
The study “Tracking Free-Weight Exercises” (incorporated herein by reference) teaches methodologies for processing the signals generated from a 3-axial accelerator during weight training exercises. It also teaches the value of instituting a calibration procedure to improve recognition of sensor signals generated by user movement.
The prior art fails to teach a user-friendly and reliable means for the user to notify/signal the start and stop events of an “exercise set”. The prior art teaches that the user must either interact with the “base station” located on the user's body (affixed to the upper arm or waist, for example), or the base station located somewhere in the exerciser's environment. It should be noted that providing notification of the start point of an exercise set is believed more important for reliable and accurate system operation than providing notification of the stop point of an exercise set. Foregoing notification of the stop event would not deviate from the teaching of the present invention.
Any movement by the user that generates sensor signals not directly attributable to the user's performance of an exercise set is defined by its nature as spurious. By way of example, the device instructs the user to perform a bench press with 150 pounds on the barbell. Accordingly, the user moves to the location of the bench press, adjusts the weight on the barbell to the desired amount, assumes the correct prone position on the bench, and finally grips the barbell with both hands in preparation to begin the exercise set. All of these preparatory movements by the user generate spurious signals that must be discriminated/identified by the device.
Accordingly, one method of minimizing or perhaps eliminating such spurious signals is to provide the user with the means of notifying the device of that moment in time and that position in space when the user is prepared to start the exercise set and when the user completes the exercise set. In this instance, “prepared to start” means the user has assumed a ready position with the user's hand or hands in position on the training device. The user “stops the exercise set” when the final repetition is completed, but the user's hand remains on the barbell. It should be noted that with certain training implements or training methodologies the ideal start and stop positions may be defined as the user's hand or hands being in close proximity rather than literally in contact with the training implement. Reliably determining the start and stop events is important for reliable and accurate data accumulating and processing.
When the base station is worn on the user's body, to provide notification (signal) of a start and stop point of an exercise set would necessitate that the user move one hand from the aforementioned start position and reach across the body to access the base station input means. This action creates spurious signals. Having the base station remote from the user's body merely compounds the spurious signals produced.
A user-friendly means for the user to input/signal/notify the start and stop points of an exercise set is important to creating a satisfying exercise experience. Reaching across one's body or especially moving to a remote base station at the start and stop points for each exercise set of a workout detracts from the experience.
The prior art teaches one means of addressing the aforementioned need for providing notification of stop and start for each exercise set to the device. Affixing the sensor to the training implement itself satisfies system notification, as only the actions of the user would cause the training implement to move. There are, however, a number of practical deficiencies associated with this approach.
First, it may be inconvenient for the user in a training environment wearing typical workout type clothing to transport a sensor and to frequently affix and remove the sensor from one training implement to another. Second, many training implements are coated with non-magnetic materials such as vinyl, plastic, rubber or non-magnetic metals, rendering magnetic mounting means impractical. Third, many exercise modalities involve the use of elastomeric cables, bands, medicine balls, shadow boxing, jump roping, heavy bags, Bodyblade® and similar that provide no suitable attachment point regardless of whether magnetic mounting or Velcro or similar attachment means are employed.
Fourth, several prior art devices teach affixing the sensor to the weight stack of a “selectorized” strength machine. However, for safety reasons, manufacturers of selectorized machines may cover the moveable weight stacks with shrouds that restrict user access to protect the user from injury to hand or fingers for product liability reasons. This may act to restrict access to the weight stack for such sensor mounting purposes.
Fifth, selectorized strength machines are designed to increase or decrease the resistance provided to the user to match the changes in the user's joint leverage during an exercise. The performance specs of cams used to control the weight stack are believed to vary between machines and manufacturers. A cam is defined as: “A cam is an ellipse connected to the movement arm of the machine on the belt or cable on which it travels. The purpose of the cam is to provide variable resistance, which changes how the load feels (but the actual weight never changes) as the lifter moves through the range of motion of the exercise. The reason the perception of the weight needs to change is that each joint movement has an associated strength curve”. It is believed that the distance traveled by the weight stack for a given load/weight and exercise pattern is not uniform among commercially available machines. Consequently, the amount of travel/movement of the weight stack for a given load/weight may not correlate accurately with actual work performed.